DE2501843A1 - DIELECTRIC GROUND - Google Patents

Description

EGG. DU PONT DE HEMOURS AND COMPANY 10th and Market Streets, Wilmington, Delaware 19 898, V.St.A.

Dielectric ground

The invention "relates to dielectric masses that are characterized by Let activation be made conductive.

The electrical treatment of masses containing metal particles dispersed in an insulating polymeric binder, to produce coatings of low electrical resistance and electrically conductive electrode layers, in which have an intimate electrical "interparticle connection" is disclosed, for example, in U.S. Patents 2,321,587 and 2 819 436 "known. Under certain circumstances" there is a need instead of a one-piece conductor to produce a plurality of separate conduction paths that are separate from one another are isolated, so that each line path is used as a connecting element, e.g. in a microprogram memory (ROM memory), can be used. In this way, the pattern of such electrical conduction paths can be used for addressing circuits the input into an electronic data processing system

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or form it for the output. Pure soTcne? For purposes of evaluation, it is essential that the various electrically conductive paths are not connected to one another during their production (crosstalk). The problem of how to obtain mutually insulated conduction paths when these conduction paths are made close together becomes important in the production of patterns of electrical conduction paths which are to be compatible with laminated layers of high density microcircuits. In order to achieve the highest density, the geometric configuration of a conduction path becomes critical. Two types of electrically conductive structures are known, namely 1) a spatial arrangement in which the particle chains are highly interconnected in the form of a three-dimensional network, and 2) a bridge-shaped arrangement in which an electrically conductive particle chain apparently runs along a single electrical breakdown path forms. Hypothetical structures that contain multiple bridge-like, electrically conductive paths side by side without interconnection, have been subjected to theoretical analysis; see, for example, "Kolloidnyi Zhurnal", Volume 28, No. 1, January-February 1967, pages 62-68. ■ "

The invention is based on the object of providing a normally insulating (dielectric) compound, which consists of a dispersed, potentially conductive, particulate filler and a polymeric binder, and from which closely spaced, electrically conductive paths can be established if the mass of a suitable electrical Treatment is subjected. Another object of the invention is to provide a new structure which is suitable for use as a ROM memory, and in which the closely spaced electrical conduction paths, which are formed by the aforementioned electrical © treatment are isolated from each other, so that there is no crosstalk comes. "

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ORIGINAL INSPECTED

OH-5418-A ₃ 2501343

Briefly summarized, the invention relates to a mass of a dielectric polymeric binder having one therein dispersed, dielectric, particulate filler that has the ability to act upon exposure to a activating potential to become conductive, the particulate Filler contains a substantial proportion of particles with smooth, rounded edges. The invention relates to also such a hatred that, when in layer form, is a multitude in electrical activation of closely spaced, electrically conductive, isolated conduction paths that run through the Extend layer through. The electrical activation can be done by applying thin layers of hatred many pairs of opposing, spaced-apart electrodes are attached to it and to adjacent ones Pairs of electrodes applies electrical voltages that exceed a characteristic breakdown voltage. Such laminates are suitable for addressing circuits in ROM memories by preventing crosstalk and ensuring reliable operation of the addressing function.

The invention relates both to the mass described above as such as well as laminates made from them. In the broadest sense, the polymeric binders can be made from many different Classes of organic polymers are selected. The polymer should have a glass transition temperature (T) of at least 40 ° C, preferably at least 100 ° C, must not and must not react with the filler particles withstand the thermal stresses encountered during manufacture the device of which it forms part. Those used for the masses according to the invention Binding agents can contain small amounts of solvents and other substances that increase their freezing temperature something, but not below .40 C, by reducing it act as plasticizers. The freezing temperature T is after

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that in "Newer Methods of Polymer Characterization", edited by Bacon Ke, Interscience Publishers, New York, 1964, on page 393 ff. Determined method described. Typical examples of organic polymers with glass transition temperatures of at least 40 ° C can be made from the known polyolefins, Polyvinyl derivatives, polybenzimidazoles, polyesters, polysiloxanes, polyurethanes, aromatic polyimides, poly (amidimides), Poly- (ester-imides), polysulfones, polyamides, polycarbonates, Polyacrylic acid nitriles, polymethacrylic acid nitriles, polymethacrylic acid methyl esters, polystyrenes, poly (α-methylstyrenes) and cellulose triacetates can be selected. Representative representatives of these groups as well as their freezing temperatures are listed in Table I. In general, the higher the glass transition temperature, the more stable the resistance the electrically conductive path that forms during activation.

Tabel

Organic polymers T, ⁰ C

Aromatic polyimide (DAPE-PMDA) 380

Aromatic poly (amide-imide) (MAB / PPD-PMDA) 265

-Aromatic polysulfone - 190

Polyurethane 150

Polycarbonate 150

Polydecamethylene azelaic acid amide 149

Aromatic polyamide (70? £ 'lP / 30 ff TP-MPD) 130

Polyacrylonitrile · ·· ·. ■ · ■ - 130

Poly (cc-methylstyrene) 130

Polymethacrylonitrile 87,

Polymethacrylic acid methyl ester 105

Cellulose triacetate 105

Polystyrene 100

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Table I (continued)

Organic polymers T, C

Polyvinyl alcohol. 85

Polyindene 85

Polyvinyl carbazole 84-85 polyvinyl chloride 82

Poly (vinyl chloride / vinyl acetate), 95: 5 71

Cellulose acetate. 69

Ethyl polymethacrylate 65

Poly (vinyl chloride / vinyl acetate), 88:12 63

Poly (vinyl chloride / vinyl stearate), 90.3: 9.7 56

Poly-p-xylene. 55

Polyvinylidene chloride / vinyl chloride) 55-75 Polypseudocumene 55

Polyvinyl pyrrolidone, 54

Cellulose Trinitrate .53

Polycaprolactam 50

Polyhexamethylene sebacic acid amide 47

Polymonochlorotrifluoroethylene 45

Ethyl cellulose. 43

Poly (styrene / butadiene), 85:15. 40

DAPE = diaminodiphenyl ether

PMDA = s pyromellitic dianhydride

MAB = m-aminobenzoic acid

PPD = p-phenylenediamine

IP = isophthalic acid chloride

TP = terephthalic acid chloride

MPD = m-phenylenediamine

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Except for the organic, essentially linear ones described above According to the invention, thermoplastic polymers can also contain certain thermosetting, crosslinked organic polymers can be used as binders such as epoxy resins.

Aromatic polyimides with glass transition temperatures of at least 100 ° C, preferably at least 150 ° C, are preferred Class of polymers which can be used as binders according to the invention. Such polyimides and their manufacture are on are known, e.g., from U.S. Patents 3,179,630, 3,179,631, 3,179,632, 3,179,633, 3,179,634 and 3,287,311. Suitable Polyimides have the general formula

O
< ^δ > Q
Il Il ti O O

N -

in the η such a large integer means that the polymer has the mechanical properties required for use as a binder, R is one of an aromatic Tetracarboxylic dianhydride derived tetravalent radical, wherein the aromatic moiety is at least one Ring having 6 carbon atoms and characterized by benzene-like unsaturation, while R 'has one of means a divalent radical derived from a diamine. Among the aromatic tetracarboxylic dianhydrides, which are used in the production Of polyimides useful in the present invention include those in which each of the four carbonyl groups of the dianhydride is bonded to a different carbon atom of a benzene ring, the carbon atoms of each Pair of carbonyl groups are bonded directly to adjacent carbon atoms of a benzene ring. Examples of dianhydrides, which are suitable for the production of binders

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Reversible polyimides are 'pyromellitic dianhydride, naphthalene-Z ^ e ^ -tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, diphenyl-2,2', 3,3'-tetracarboxylic dianhydride, 2,2-bis- ( 3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, benzophenone 3,3 », 4,4 · -tetracarboxylic dianhydride and diphenyl-3 ₁ 31 ₁ 4 ₁ 4» -tetracarboxylic dianhydride.

Organic diamines suitable for the production of polyimides which can be used according to the invention are those of the general formula H ₂ N-R'-NB ^, in which the divalent radical R ^{1 can be} an aromatic, aliphatic cycloaliphatic ^ aromatic-aliphatic, heterocyclic radical or an organic bridging radical , in which the bridging atom can be carbon, oxygen, nitrogen, sulfur, silicon or phosphorus. The rest of the R ^! can be substituted or unsubstituted in a known manner. Preferred radicals R ¹ are those which contain at least 6 carbon atoms and are characterized by benzene-like unsaturated bonds, for example p-phenylene, m-phenylene, biphenylene, naphthylene and the rest

where R "is an alkylene or alkylidene radical having 1 to 3 carbon atoms, denotes an oxygen atom, a sulfur atom or the radical SOp. . ■.

The diamines described above can also be used to produce polyamides which can be used as binders according to the invention. The diamines which are preferred for the production of the polyamides and polyimides which can be used as binders according to the invention include m-phenylenediamine, p-phenylenediamine, 2,2-bis- (4-aminophenyl) .- propane, 4-, 4 -'- diaminodiphenylmethane, benzidine, 4,4'-Diaminoaiphenylsulfid, 4.4 ^{f-diaminodiphenyl} sulfone, 3,3'-diaminodiphenyl sulfone and 4.4 ^t -Diaminodiphenyläther.

80982Ö / 06 2

• fr.

Some polyimides are not easy to process because their melting points are too high. In such polyimides must the metal particles required according to the invention in the Manufacturing to be stored. For example, the metal particles can be added to the polyamic acid containing a Forms a processable intermediate product in the manufacture of the polyimide. As is known, polyamic acids dissolve in suitable ones Carrier solvents. In such methods, the metal particles can be immersed in a polyamic acid in a carrier solvent dispersing, and the amounts of polyamic acid and metal particles are calculated so that the Converting at least a portion of the polyamic acid to the polyimide and removing at least a portion of the carrier solvent forms the above-described composition of polyimide and metal particles. Such compositions of polyamic acid, carrier solvents and metal particles have dielectric properties and can be removed prior to the conversion of the polyamic acid to the polyimide and the removal of the carrier solvent deform as desired.

A particularly preferred polyimide with a glass transition temperature of 380 ° C. can be prepared from the corresponding polyamic acid as an intermediate in N-methyl-2-pyrrolidone (commercially available as "PYRE-M.L." - wire enamel RC-5057) Polyimide which forms from such a polyamic acid and contains aluminum particles in dispersion for a short time tolerates a Temperature of 450 ° C and long-term one of 220 ° C.

Aromatic polyamides with the required glass transition temperature are described in U.S. Patents 3,006,899, 3,094,511, 3,232,910, 3,240,760 and 3,354,127. Such a polymer, which can be used according to the invention, can be represented by the formula —f — COCgH ^ CONHCgH ^ NH -} - - , in which η is a large integer. Particularly preferred is a polymer of this formula in which the -COCgH ^ CO units isophthaloyl and / or terephthaloyle units and the -

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Units are m-phenylenediamine units. Such an aromatic polyamide, which is particularly preferred as a binder, is obtained by reacting equimolecular amounts of m-phenylenediamine and phthalic acid chloride, the latter being a mixture of about 70 mol percent isophthalic acid chloride and 30 mol percent terephthalic acid chloride. Such a polymer having a glass transition temperature of 130 ⁰ C is stable at 300 ° C for a considerable period of time and can be conveniently in the form of a solution having dispersed therein a metal powder for laminates handle.

The filler particles used in the compositions according to the invention are non-conductive, but have the ability to act under the influence of an activating electrical potential to form electrically conductive Viege, and are characterized by that they have rounded edges along their surface. The electrical contact resistance prevents activation before activation the passage of electrical current from one particle to another when the particles are in the polymeric binder touch. In general, the particles have an electrical characteristic conductive interior and a dielectric surface due to which there is contact resistance when the Particles touch each other so that 'no electrical Form conductive paths by contacting the particles in the binder. With electrical activation the dielectric surface collapses and no longer causes the formation of a contact resistance between the particles, so that an electrical contact is made between the particles along a bridge-shaped path. That electrically conductive interior of a filler particle can be a Be metal or a semiconductor. The conductivity state can be fully conductive (10 to 10 ~ ^ ohm · cm) or semiconducting (10 to 10 ohms «cm). Usually metals are used to obtain highly electrically conductive bridge conduction paths, while semiconductor particles are sometimes suitable, when characteristic semiconductor properties such as a

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negative temperature coefficient of the electrical resistance.

The dielectric surface that makes the tulle particles non-conductive makes can "by coating the particle surface with an insulating chemical compound of the to be coated Metal, such as an oxide, sulfide or nitride of the metal. Easily available metals with are coated with an oxide layer, which makes the aggregate of particles in the binder electrically insulating, are aluminum, Antimony, bismuth, cadmium, chromium, cobalt, indium, lead, magnesium, manganese, molybdenum, mob, tantalum, titanium and tungsten. A preferred metal is aluminum with a tarnish film of insulating aluminum oxide that can easily be exposed to the atmosphere forms. Suitable semiconductors which can easily be coated with an insulating oxide film by oxidation are silicon and selenium.

In order to produce the masses and structures according to the invention, at least a certain part of the filler particles must be smooth, have rounded edges. Particles with smooth, rounded edges can be easily identified as two of the five known pigment particle shapes, including metal particles, belonging to identify which are spherical, cubic, is lumpy, needle-shaped and lamellar particles. To select particles with shapes suitable for the mass according to of the invention are suitable, one only needs on the one hand between the classification groups of spherical and lumpy Particles and, on the other hand, to distinguish between the other three classification groups, which are sharp particle edges are common. The cubic shape is the usual crystalline shape with sharp edges. Acicular particles .are at least several times longer than their smallest dimension and resemble a needle or a stick. The lamellar. are extremely thin plates or scales that form sometimes overlap or spread out leaf-shaped and

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almost coherent layers ". The classification is routinely done by visual inspection under a microscope or made by photographic means by scanning with the electron microscope. Under certain circumstances you can also use other methods, e.g. due to a higher tap density, reduced Use viscosity in liquid suspension or greater mobility when testing with the electric vibrator, to distinguish between particles with rounded edges and those with corners or sharp edges or even to separate them from each other.

Which is based on the natural crystalline form of the subject Metal-based species-specific shape can be modified to spherical shape using certain known techniques or lumpy particles. In general, metal particles wet milling to obtain particles that have smoother or rounder edges than dry milling manufactured particles. Powdered solids can be reduced in particle size and the particles can have a Round shape can be given by putting them in the "Micronizer" grinder ground with a circular chamber. The solids are blown into the mill with compressed air or under high pressure steam, so that the particles with very crash at high speed. The fine grain is discharged through an opening in the middle of the mill and is generally smoother and more uniform than that obtained by barrel milling or dry milling. Such Milling processes are suitable for producing spherical metal particles and, when applied to certain metals, which are easily fragile due to their crystal form, such as relatively brittle antimony or bismuth, for Generation of lumpy or rounded, irregularly shaped particles through a combination of crushing and grinding effects.

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If the melting point of the metal is low enough, you can spherical or lumpy particles by atomizing the molten metal and then usually sieving it out for the purpose of controlling the particle size. Aluminum powders obtained by atomization are usually lumpy and can however, depending on the atomization conditions and the further treatment, they can also be produced in spherical shape. Metal powder, which is characterized by a smooth, spherical particle shape mark, are commercially available, such powders can be packed to a high density, thereby dispersing the metal in the polymeric binder is simplified.

Not all particles of the filler need have smooth edges; mixtures of particles with smooth edges and with sharp edges can also be used. Even 30 percent by weight, preferably at least 50 percent by weight, of smooth-edged particles in the particulate filler are sufficient to practically prevent crosstalk between spaced-apart conduction paths that are formed by activation of the compound according to the invention. In order to avoid any possibility of crosstalk, practically all particles, ie about 100 % of the particles, should be smooth-edged. The smooth-edged particles should preferably not have any points.

The mean size of the filler used according to the invention Particle is in the range of about 0.01 to 250 u. The smaller the thickness of the layered mass should be, the more the particle size must be smaller. Generally exceeds the particle size is not 0.1 times the layer thickness. Particles that pass through sieves with mesh sizes from 44 to 149 w, have the preferred particle size. Smaller particles sometimes limit the conductivity that can be achieved through exposure an activating voltage on the dielectric mass, and larger particles limit the me-

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0R-541.8-A- _% ^ ■ 250Ί8Α3

mechanical strength of the mass and the degree of surface smoothness, which can be obtained with a layered mass. In the case of the preferred masses, the particle shapes can be from the industrially available cigar-shaped (lumpy) particles, in which no sharp edges can be seen in a typical stereo image made with an electron microscope are to substantially spherical particles with smooth, rounded outlines.

The filler particles are in bulk according to the invention Contained in sufficient quantity to produce electrical activation which can be achieved by a sudden initial Indicates transition to a state of low electrical resistance; but the amount shouldn't be that big be that the mechanical strength of the binder is impaired. The appropriate amounts of particles depend on the type of electrically conductive particles provided with the insulating coating and are in the range from about 10 to 90 percent by volume of the dielectric mass. When using with an insulating coating Metal particles, it is advisable "to use them in amounts of at least 35 percent by volume so that they can be activated during activation Form conductive paths of low resistance. Quantities greater than 90 percent by volume can make the mass crumbly and make the surface of a layered mass uneven. Furthermore, when sharp-edged and smooth-edged particles are used together, their relative sizes should be in Combination with their relative proportions can be chosen so that the crosstalk between the conduction paths is essentially is avoided if the mass, as described here, forms a large number of spaced apart electrically conductive paths is activated. In general, the size of the sharp-edged particles should be in proportion to that of the smooth-edged particles should not be so large that there is a bridging or a short circuit comes between neighboring activated conduction paths.

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In general, the size of the sharp-edged particles in their largest dimension between the sharp edges Do not exceed the size of the smooth-edged particles.

The normally insulating mass according to the invention is A shape-retaining solid material considering the stiffness of the binder. The solid substance can have several physical properties Forms are available. For example, it can be used as a coating, film or surface on any suitable non-conductive support or in the form of a self-supporting film of regular or irregular shape. The mass can according to known methods for homogeneous distribution of a filler in a polymeric binder. Well-known methods can also can be used to bring the mass into the form of a layer of any thickness and shape. For example can a coating of the mass on a carrier by painting, spraying, dipping or other conventional methods Apply methods that include drying by evaporation. When the polymeric binder is easily meltable is, a layer of the polymer melt containing the dispersed metal particles can be poured or extrusion onto a carrier. Otherwise you can cast a film on a carrier and then it peel off from the carrier.

If a high-melting polyimide is used as a binder, it may be more expedient to use this binder in the form of the polyamic acid obtained as an intermediate product in solution to be processed in a suitable solvent. Such a polyamic acid solution can be used for those described above Layering methods can be used. The solvent for the polyamic acid is said to be compatible with both the polyamic acid as well as strongly associate with the polyimide, which is then produced from it, and can be removed by volatilization be. Suitable solvents are Ii, N-DimethyIform-

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• ft * .

amide, Ν, Ν-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone and tetramethyl urea. After transfer to the In layer form, the polyamic acid can easily be converted into the polyimide on the spot by heating, with a Ring closure takes place with elimination of water; the carrier solvent is also driven off at the same time.

The mass according to the invention generally becomes one Layer deformed. The shape and the dimensions of the layer are not particularly important, since the one you are after Processing to an electrically conductive element intended function not from its mass, but from its ability depends, wire-like inner conduction paths of low resistance between closely spaced pairs of opposite one another Electrode contacts on the same side or on opposite sides of the layered mass to build. The layer thickness varies with the intended use, but is usually in the range of about 0.1 up to 10,000 u, usually in the range from 1 to 2000 u Ground has an electrical resistance of at least 10 ohms between flat electrodes.

A preferred method of electrical activation is the application of a short pulse of direct current, usually from 1 microsecond to 1 millisecond duration on the component. the The polarity of the pulse is irrelevant. When the thickness of the barrier layer is less than 25µ, one is usually sufficient Voltage from 5 to 15 V. For larger thicknesses, voltages of up to several hundred volts may be required. Preferably the current strength is limited to about 100 mA; however, a limitation to lower currents may also be necessary when sensitive parts are in the path of the current.

The -electrical activation can also be achieved by briefly ' Apply AC voltage. In this case

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<> it-5 «ia-A. _{4 &} 25018A3

the action should not be significantly shorter than 1/2 period be. In other respects the procedure is the same as that described above for "DC Activation".

In establishing a pattern of electrical conduction paths, numerous pairs of conductor electrodes are usually permanently attached to the electrically activatable structure and suitable activating electrical potentials are applied to one electrode pair at a time, to electrode groups at a time, or to all electrode pairs at the same time. The spatial arrangement can be so dense that the distance is only a fraction of 25 jx, for example 0.25 yU, and usually, in order to obtain electrical conduction paths of highly dense packing, is no more than about 1.3 mm. The sequence or the timing of the production of the electrical conduction paths between the contact points of the conductor electrode pairs is not critical; but under certain circumstances in the production of tight arrangements of closely spaced conduction paths, the heat accumulation during activation can impair the mechanical stability of the structure if all conduction paths or even only the] conduction paths of a group are produced at the same time. When the electrically activatable structure is a layer, pairs of electrodes are usually attached opposite one another on the top and bottom of the layer. The electrical activation then generally forms many parallel electrical conduction paths which run perpendicular to the surfaces of the layer. In general, the thinner the layer, the closer the parallel paths can be. In layers in which particles (as defined according to the invention) are used, the ratio of the electrode distance (path distance) (s) to the layer thickness (t) can be approximately 1: 1. If there is reliable isolation between adjacent conduction paths, even lower ratios can be used. In layers in which only sharp-edged particles

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are used, a ratio s: t of about 5: 1 is required for equivalent insulation. However, the two electrodes of an electrode pair can also be attached to the same layer surface so that they are adjacent to one another but not touching one another. When many electrode pairs are arranged on a surface in this way, electrical conduction paths can be formed that are flat and run parallel to the surface in question. With such a surface arrangement, the conduction paths do not necessarily have to run parallel to one another. By choosing the appropriate attachment points for the electrode pairs, combinations of electrical conduction paths can be generated which run on the surface of an electrically activatable structure and also through its interior. The shape, cross-sectional area, size and shape of the electrodes hardly make any difference in the process stage of electrical activation; For example, you can use silver, copper and gold paints, copper wire (e.g. 0.254 mm and 1.02 mm in diameter), straight pins, self-adhesive metal foils on the back, rounded spring-loaded pressure contacts or alligator clips. The cross-sectional area must be small enough so that the electrical conduction paths can form in the desired density so that adjacent pairs of electrodes do not touch each other. For example, a 0.254 mm thick copper wire has a sufficiently small diameter for use in forming electrical conduction paths that are isolated from one another and spaced approximately 1.3 mm from one another. For the formation of electrical conduction paths that are at a distance of less than 25 μ from one another, needle-shaped electrodes or electrodes produced photographically are suitable.

The mass according to the invention is suitable in layer form for Making the desired arrangement of close together lying, but isolated from each other electrical conduction paths. Such an arrangement can be made with the help of suitable

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OR-5418-A. '

th electrodes provided reading devices are electrically tested and read out. Such a structure can e.g. Identification or credit card for identifying people or devices, for displaying credit values or other information be. It is also suitable in series connection with spatially correlated diode or transistor elements for manufacture a ROM memory in which each electrically conductive path acts as a connection element to a diode or transistor serve and selectively feed information to an electronic data processing system or extract it from it. When the mass according to the invention in layer form in direct contact with an arrangement of diode or transistor elements stands, the metal of the filler particles should be chosen so that it is in contact with it Semiconductor surface is compatible. The metal chosen can be a nondoping agent for the underlying semiconductor surface be. But it can also be a dopant, provided that the conductivity type it is normally used for is the same as that used by the semiconductor surface in the formation of the diode or transistor element receives. For example, it is known that aluminum is a p-type dopant and antimony is an n-type dopant for silicon is. An aluminum-containing layer is therefore compatible with diode elements with p-type silicon surfaces, and a layer containing antimony Layer is with diode elements with n-silicon surfaces compatible.

example 1

A. Different amounts of commercially available aluminum powder, which has particle sizes of about 2.5 to 50 ti and smooth, almost spherical particles are below Stirring in a Ν, Ν-dimethylacetamide solution of a polycondensation product of high molecular weight from equimolecular amounts of m-phenylenediamine and a mixture of 70 parts of isophthalic acid chloride and 30 parts of terephthalic acid chloride dis-

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pergates. The polymeric binder has a glass transition temperature of 130 ° C. Each mixture is then poured onto a polytetrafluoroethylene-coated plate which has been preheated to 50 ° C, whereupon the mixture is heated to 150 ° C to drive off the solvent and form a film to manufacture. Each film is then pressed using a polytetrafluoroethylene-coated iron heated to 150 ° C. in order to smooth the surface. The thickness is not significantly reduced by the pressing. The films are labeled A and E in Table II. 1 part by weight of an aluminum powder (particle size about 7 to 60 u) with not leaf-shaped, but sharp-edged lamellar particles is added to the masses used for the production of films D and E in order to prevent the influence of the mixing of smooth-edged and sharp-edged particles on the mutual isolation of the detect electrical conduction paths formed during the electrical activation of the film. The test procedure for the various film samples is as follows: A test device in which two electrical conduction paths can be made about 1.3 mm apart at the breakdown potential (DS) given in the table creates a conduction path with a resistance of FLj ₂ ohms between the first pair of opposing electrodes and R, ^ ohms between a second pair of electrodes. Resistance measurements are made with a Keithley Model 200B DC electrometer with a current shunt resistor, Model 2000. In all films, the resistance FL, * between the two cable paths is measured and exceeded

12th
10 ohms, which confirms the complete mutual isolation of the closely spaced electrical conduction paths that have been formed by electrical treatment of the relevant masses. The presence of sharp-edged particles in the same amount as the smooth, round, spherical particles does not interfere with the insulation of the conduction paths.

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Tabel

II

Film together
setting: connective
middle / filler,
Parts by weight filler Vol.-96 .. Thickness,
mm DS, volts (A) 0.4 / 8 Wt% 90 0.457 300 (B) 0.15 / 2 95 87 0.762 150-500 (C) 0.15 / 2 95 87 0.864 400-500 (D) 0.23 / 1 ** 93 81 ** 0.635 2-50 (E) 0.23 / 1 ** 90 ** 81 ** 1.473 300-400 90 **

* Density = 1.32 ** Also contains 1 part sharp-edged powder.

^ 12 or R ₃₄ ,
Ohm All in all
checked number
from R23
= infinite
lich % R ₂₃ =
infinite
lich 25th - 50 . 6th 6th 100 200 - 1500 40 40 100 65 - 89 6th 6th 100 100 - 350 - 6th 6th 100 450 - 600 6th 6th 100

B. One works according to part A, but with the weight ratios of an aluminum powder given in Table III non-leaf-shaped, but sharp-edged particles. The resistance Rp ^ between the at a distance of 1.3 mm from each other standing electrically conductive path decreases for the specified

12 Percentage of attempts on less than 10 ohms.

From the above data it can be concluded that the compositions according to Part A are suitable for the production of a thin layer structure in which electrical

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0R-5418-A

Four, many close together, isolated from one another Let establish electrical conduction paths, and that a conduction path generated in this way as a connecting element in a ROM memory can serve. In contrast to this, the masses produced with sharp-edged particles according to Part B are for the reliable Performance in an electronic data processing system unsuitable without crosstalk unless the ratio s: t is increased to about 5: 1.

Tabel

III

Film together
setting: bandage
medium / filler, 0.15 / 1.5 * filler Rj 2 or
ohm ^R 34 ^{] 1} total
checked Thickness, DS, volts Parts by weight 0.23 / 1.5 96 vol% by weight 50 - 100 9 mm 150-250 (P) 0.23 / 1.5 .91 83 2000 - 5000 6th 0.762
up to 0.508 200 (G) 0.23 / 1 87 77 2000 - 3000 6th 0.762
to 0.889 150 (H) 0.3 / 1 87 77 750 - 1100 6th 0.254
to 0.305 250 (D 81 68 700 - 2000 6th 0.838 300 (J) 77 63 0.889 * Film made by melt pressing. ^R 23 ~
infinite
lich number
from R23
= infinite
lich 78 (F) 7th 50 (G) 3 . 100 (H) 6th 67 (D 4th 67 (J) 4th

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OR-5418-A
Example 2

Further mixtures of smooth-edged and sharp-edged particles are dispersed in the solution of the polymeric binder, and the masses are made into films according to Example 1 shed. Two pairs of opposing contact electrodes (made of 0.254 mm thick copper wire) are placed at a distance 1.3 mm from each other on the opposite surfaces of each of the mim specimens thus prepared. The electrical activation of the two electrical conduction paths passing through each film is by applying a fixed breakdown potential of 300 Y first between one pair of the opposite Electrodes and then accomplished between the other pair of opposing electrodes. Table IT gives the mean thickness of the multiple films of each composition in millimeters, the mean resistance of the two formed by applying an electrical potential of 300 Tf electrical pathways, the number of films of each examined for insulation of electrical pathways Composition, the percentage of "pairs of electrical conduction pathways that are completely isolated from one another show, and the percentage of smooth-edged particles (based on the total weight of the filler particles) at. The evaluation of the test results given in the table shows that even .30 # of smooth-edged particles in the mixture of smooth-edged and sharp-edged filler particles are sufficient for complete mutual insulation to achieve the spaced apart electrical conduction paths.

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0R-5418-A

Film composition: Binder / filler ^ /

Filler2 »wt .-%

.23.

Tabel

IV

Filler, vol -96

Thickness, mm

(K) 13/9/78 34 ' 3 * 77 the % of Versu 0.559 (L) 14/17/69 75 try che with iso 0.711 (M) 7/28/65 340 87 8th lation 0.686 (N) 13/35/52 410 77 7th 62.5 0.711 (ο) 7/37/56 410 87 * 6 71.4 0.584 (P) 7/74/19 390 87 7th 100.0 0.533 340 number 7th 100.0 Wt% ^R 12 ^{ocie: r} 900 7th 100.0 smoothness ohm 100.0 Particle (K) 210 - 10 (L) 270 - 20th (M) 290 - 30th (N) 190 - 40 (0) 230 - 40 (P) 100 - 80 B e i s ρ i e 1

The film production and the test are carried out according to Example 1 with three aluminum powders of different particle sizes e as fillers. The particle sizes of the aluminum powders are 7 to 70 µ, 4 to 20 µ and 1 to 10 µ, respectively. The powders will be examined on the basis of stereo recordings made with the electron microscope, which shows that they all consist of consist of spherical particles with round, smooth surfaces, and that some of the particles are cigar-shaped. A complete test results from the test according to Example 1 Isolation of the electrical conduction paths that are approximately 1.3 mm apart. These data can be found in the table V. ·

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609825/0620

OR-5418-A

Film composition: binder / filler,
Parts by weight

(Q) 0.15 / 2 (7-70 p)
(R) 0.15 / 2 (4-20 p)

(S) 0.15 / 2 (1-10

Table V

filler

Wt% vol Ji

93 93

93

87 87

87

Thickness, mm

0.889

0.762 to 1.143 1.397

DS, volts

250-400 250-300

450

or
ohm

15 - 80

25-300

7000-15000

Overall checked

13th

Number of R ₂₃

= infinite -

13th

% R

23 "unend Lich

100 100 100

Example 4

Following the procedure of Example 1, a thin film is produced, the spherical filler particles made of cadmium with a ratio of binder to filler of 0.15: 1 (corresponding to 53 percent by volume of cadmium). The results can be found in Table VI.

T a b e 1 1 e VI

R ₁₂ * or R ₃₄ *, All in all number % R ₂₃ -
infinite Ohm checked from R ₂₃
β infinite lich DS, volts 2800-4000 6th lich 100 200 900 - 1200 6th 6th 100 250 6th

* Average of six experiments.

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609825/0620

OR-5418-A ■

• ar-

Example 5

Further films having the same weight ratio of aluminum powder to binder as in Example 5 can be made by using a polyaemic acid as an intermediate in the formation of the binder acting polyimide mm, 0.074 mm or 0.044 mm according to Example 3 in each case in 16.5 percent solutions of a commercially available polyamic acid ("Pyre-ML" wire enamel RC-5057, polymer solids converted to 15.2 <fo ) in N-methyl The three paint dispersions are poured onto a smooth surface, then heated to 135 ° 0 for 0.5 hours and then to 300 ° G for 1 hour in order to complete the formation of the polyimide as a binder for the dispersed aluminum particles to cause the carrier solvent and the water split off during the condensation of the polyamic acid to form the polyimide to evaporate Cured films are suitable as thin-layer structures in which a large number of closely spaced, isolated electrical conduction paths can be produced by electrical activation (according to Example 1), which are suitable as connecting elements for ROM memories.

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609825/0620

Claims (10)

E.I "du Pont de Nemours and Company OR-5418-A Claims ! electrical ground, characterized in that it consists of '"· ** ■' a dielectric organic polymeric binder, the polymer of which has a glass transition temperature of at least 40 ° C. and, normally dielectric, dispersed therein Filler particles made of aluminum, which form a tarnish film of aluminum oxide than when exposed to one having activating potential electrically conductive dielectric coating and at least 30 percent by weight have smooth, rounded edges. 2. Dielectric mass in the form of a layer with a thickness of 0.1 to 10,000 μ and an electrical resistance of at least 10 ohms, which is capable of, when electrically activated, a multitude of closely spaced apart to form standing, mutually insulated electrical conduction paths through the layer, characterized in that that it consists of a dielectric polymeric binder, the polymer of which is an organic polymer a glass transition temperature of at least 40 ° C, and normally dielectric filler particles dispersed therein which has an electrically conductive interior made of metal or a semiconductor and a dielectric surface coating comprise an insulating chemical compound of the metal or semiconductor and at least 30% by weight have smooth, rounded edges. 3. Dielectric mass according to claim 2, characterized in that it consists of 10 to 90 percent by volume of binder - 26 - ■■ .. ·. B0 9825/062 0 0R-5418-A and the corresponding 90 to 10 percent by volume of filler particles, the spherical or lumpy shape have, and that the polymer of the binder has a glass transition temperature of at least 100 ° C. 4. Dielectric mass according to claim 3, characterized in that the filler particles have a mean size
Range from 0 ^ 01 to 250 u. 5. Dielectric mass according to claim 3, characterized in that it consists of at least 35 percent by volume of filler particles consists, of which at least 50 percent by weight have smooth, rounded edges. 6. Dielectric mass according to claim 3, characterized in that the polymer is a polyamide. 7. Dielectric mass according to claim 3, characterized in that the polymer is a polyimide. 8. Dielectric mass according to claim 4, characterized in that the particles are spherical aluminum particles and the polymer is a polyamide. 9. Dielectric mass according to claim 4, characterized in that the particles are spherical aluminum particles and the polymer is a polyimide. 10. Dielectric mass according to claim 2, characterized in that the mean particle size of the filler particles is not greater than 0.1 times the layer thickness. - 27 - 609825/0620